The present invention relates generally to apparatus for use with telephone PBX systems. More particularly, the present invention relates to a telephone line concentrator without a switching matrix (TABX) for use in conjunction with a PBX system for monitoring the various telephone extensions within the PBX system and instructing the PBX to answer the call by means of a remotely located telephone answering service.
In telephone PBX systems, it is desirable to provide telephone answering services for each of the various telephone extensions within the system such that incoming telephone calls can be answered and provision made for responding thereto. That is especially true where an incoming call remains unanswered, indicating that the called individual is not available to answer the extension.
In the past, in order to provide each of the telephone extensions of a PBX system with telephone answering services (TAS), the telephone answering service was connected across both the tip and ring lines and had no connection whatsoever to the PBX.
In another device, described in commonly assigned U.S. patent application Ser. No. 06/599,715 entitled "Telephone Answering System With Line Detector," a control system has been interconnected between the PBX system and each of the telephone extension lines. That control system is connected in parallel across the tip and ring lines directed to each extension line. The control system monitors each of the incoming calls received on the telephone extension lines and uses the PBX/Centrex switching matrix for connecting a local operator-controlled telephone answering system to the tip and ring lines of such an extension, when that extension remains unanswered for a predetermined number
The present invention, on the other hand, while also being connected in parallel across the tip and ring lines, again uses the PBX/Centrex switching matrix (instead of its own switching matrix) but interfaces to a nonlocal (remote) operator-controlled telephone answering system.
In operation, the TABX is connected across each of the extension lines in the PBX system and counts the number of rings on each respective extension line therein. When a telephone rings more than a predetermined number of times, the TABX of the present invention instructs the PBX to perform a directed call pick-up by means of its connection to the PBX. That results in the call currently ringing on that particular extension being placed on the line connecting the TABX to the PBX. At the same time, the TABX goes off-hook and dials a DID number on another line connected to the telephone company (Telco). Once the dialing is completed, the TABX connects the voice path represented by its line to the PBX to the line to the Telco. This allows the operator controlled telephone answering system to be remote.
Since the present TABX is designed to facilitate the operation of a telephone answering service with a PBX, the DID number it dials to the Telco would desirably be a unique number to the telephone answering service. That telephone answering system may be located either locally or remotely from the TABX. It may also be a corporate message center or the message center for a building.
Unlike existing telephone line concentrators, the invention does not need to have its own switching matrix. Instead, it uses a novel combination of hardware and software in order to utilize the switching matrix of the PBX. In addition, rather than being connected to the input side of the PBX, the instant invention is connected to the output side of the PBX, namely, to each of the various telephone extensions within the PBX system. Further, unlike a conventional line concentrator, the TABX is able to use "dial-up" rather than dedicated telephone lines for remote voice paths. Such novel combination of features offers substantial cost savings over prior art telephone line concentrators. Further, since the TABX uses a telephone line ring scanning hardware device which itself is connected in parallel across the tip and ring lines of each of the various telephone extensions within the PBX system, it is only necessary to add an additional line ring scanner for each of the various telephone extensions in order to cover all of the many (sometimes several hundred) telephone extension lines within a PBX system.